Polyurethane Dispersion Gas Barrier Adherence
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Solution Overview
Problem
Conventional polyurethane films with gas barrier properties face challenges such as toxicity, poor humidity resistance, and reduced flexibility, while existing methods for improving adherence, like blending alkoxysilyl compounds, result in coagulation and poor layer formation.
Innovation Solution
A polyurethane dispersion is developed by reacting an isocyanate group-terminated prepolymer with a chain extender containing an alkoxysilyl compound, using xylylene diisocyanate and a low-molecular-weight polyol with a functionality of three or more, ensuring excellent dispersion and adherence properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PVDC is used to achieve excellent oxygen gas barrier properties, then gas barrier properties are improved, but toxic gas is generated during combustion
Solution Approach 1:
The patent replaces PVDC (which has good gas barrier properties but generates toxic gas) with a polyurethane resin containing specific polyol components (C2-C8 alkylglycol and low-molecular-weight polyol with functionality≥3). This conversion maintains excellent gas barrier properties while eliminating toxic gas generation during combustion, transforming a harmful material into a safe alternative.
2Object-generated harmful factors
If polyvinyl alcohol and ethylene-vinyl alcohol copolymer are used to replace PVDC, then toxic gas generation is reduced, but gas barrier properties deteriorate under high humidity
Solution Approach 1:
The patent changes the chemical composition parameters of the polyurethane resin by incorporating specific polyol components (C2-C8 alkylglycol and low-molecular-weight polyol with functionality≥3) in controlled ratios. This parameter optimization maintains hydrophobicity and gas barrier properties even under high humidity conditions, overcoming the limitation of conventional polyvinyl alcohol-based films.
3Reliability
If inorganic oxide vapor deposition is applied to improve gas barrier properties, then gas barrier properties are improved, but flexibility is reduced and cracks may form during secondary operation
Solution Approach 1:
The patent uses a flexible polyurethane resin coating film instead of rigid inorganic oxide vapor deposition. The polyurethane resin forms a thin, flexible layer that provides excellent gas barrier properties while maintaining the flexibility and elongation of the substrate, preventing crack formation during secondary operations like folding or stretching.
4Strength
If alkoxysilyl compound is blended to improve adherence, then adherence is improved, but polyurethane resin coagulates and homogeneous layer formation is poor
Solution Approach 1:
The patent optimizes the molecular structure and ratio of polyol components (C2-C8 alkylglycol and low-molecular-weight polyol with functionality≥3) to control the hydrophobicity and molecular weight distribution of the polyurethane resin. This parameter control prevents premature coagulation of the alkoxysilyl compound, allowing homogeneous dispersion while maintaining excellent adherence to the substrate.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The polyurethane laminate exhibits improved gas barrier properties and adherence, maintaining performance under high humidity without coagulation issues, making it suitable for applications like food and pharmaceutical packaging.
Implementation Method 1
the isocyanate group-terminated prepolymer is produced by at least allowing a polyisocyanate component containing xylylene diisocyanate and/or hydrogenated xylylene diisocyanate to react with a polyol component
Implementation Method 2
polyurethane resin produced by reaction of an isocyanate group-terminated prepolymer with a chain extender
Implementation Method 3
polyurethane dispersion in which polyurethane resin produced by reaction of an isocyanate group-terminated prepolymer with a chain extender is dispersed in water
Implementation Method 4
a polyurethane layer laminated on the substrate and made of the polyurethane resin, wherein the polyurethane layer is formed by applying and drying the above-described polyurethane dispersion
Data Source
Figure 1~2
AI summary
A polyurethane dispersion is a polyurethane dispersion in which polyurethane resin produced by reaction of an isocyanate group-terminated prepolymer with a chain extender is dispersed in water. The isocyanate group-terminated prepolymer is produced by at least allowing a polyisocyanate component containing xylylene diisocyanate and/or hydrogenated xylylene diisocyanate to react with a polyol component containing diol having 2 to 6 carbon atoms, a low-molecular-weight polyol having a functionality of three or more, and an active hydrogen group-containing compound containing a hydrophilic group. The chain extender contains an alkoxysilyl compound having a primary amino group, or a primary amino group and a secondary amino group, and the molar ratio of the hydroxyl group in the low-molecular-weight polyol having a functionality of three or more is less than 25% relative to a total mol 100% of the hydroxyl group in the polyol component.